1. Field of the Invention
The present invention relates to information retrieval systems in which continuously transmitted information from a remote data base may be selectively grabbed or captured for obtaining the processing control instructions for a microprocessor controlled terminal as well as capturing selected data to be processed and displayed by that terminal with the selected purpose or processing control of the terminal being locally variable.
2. Description of the Prior Art
Computers and other types of programmable devices are well known in the data processing art and in the communications field in general. These prior art systems function in accordance with a stored set of instructions or programs or a series of programs, such as in a typical IBM Operating system or OS. In such systems, however, the programming is accomplished at the central computer whose function may be varied only by variation in the program which is loaded thereinto. Due to the high cost of computers, the art of time sharing has developed, which, through teleprocessing, has enabled a plurality of users to share a common centrally located computer by use of remote input/output devices. However, such time sharing still requires the users to be bound by the particular program which is stored in the central computer so that the plurality of users essentially share the same program functions which process their individual data inputs in accordance therewith. There are some prior art systems which are capable of obtaining a remotely stored program, however, no such systems are known to the inventors, other than that described in the commonly owned co-pending U.S. pat. application Ser. No. 611,927, filed Sept. 10, 1975, entitled "Information Retrieval System Having Selectable Purpose Variable Function Terminal," which are capable of both receiving selectable continuously transmitted frame or row grabbable video displayable data as well as continuously transmitted control instructions for processing such data over a common television distribution system normally used for such data, nor are any such systems known to the inventors in which remote local terminals connected to a remote central data source in such a common television distribution system can function in accordance with any one of a plurality of locally selected purposes or functions to provide a selected purpose variable function terminal in which the selected purpose or function may be locally varied electronically without the user having to actually reprogram his terminal. Moreover, there are no such terminals known to the inventors in which a video communication system which enables the video display of information, such as over a CATV system, may also be converted to such a local selectable purpose variable function terminal in which desired control programs may be electronically called up or retrieved from a remote central processor for local storage and operation in accordance therewith wherein both the data and the program information are transmitted as pseudo video scan lines, each containing a complete self-contained packet of information. Such a video communication system in which individual frames may be grabbed for video display thereof and updated on a row-by-row basis is described in the commonly owned previously issued U.S. Pat. No. 3,889,054, issued June 10, 1975, in which pseudo video digital data scan lines are transmitted continuously from a central data source in a one way communication system. Such a system may be controlled locally by a microcomputer as described in the co-pending U.S. Pat. application entitled "Improved Row Grabbing System," filed Sept. 10, 1975, bearing U.S. Ser. No. 611,843. As will be described herein, such video communication systems, as those employing a local microcomputer, have not been utilized to full advantage as a selectable purpose variable function terminal in which processing of data in accordance with any desired selected function, which may be varied, can be accomplished as well as the display of video data therefrom. The present invention is an improvement on such systems, as well as on the aforementioned U.S. Pat. application Ser. No. 611,927, so as to provide such an improved selectable purpose variable function terminal.